IMHO it all depends on what you can do with the sample and how much said sampler can handle (File size).
For me I have a Kurzweil 2500s keyboard sampler. At the time of purchase, I didnt have a computer. So my hardware sampler was all I had. I made the best of it. A few years later I started using Audio editing software. Specifically Acid. What I found my self doing was using it a one GIANT sampler. On my kurzweil I had a total of 35 seconds of sample time in MONO. With a computer your have INFINATE amount of sample time.
Things that are important:
Most hardware sampler have alot of built in things that help make your sound what you want it to be, examples of this would be, Filters,FX, Layering,Streching etc., all in one unit.
While alot of software samplers give you the same. In most cases your relying on Plug-ins. So its really up to how much your willing to learn.
Now to answer your question directly. I use both. I chop it on ACID (not really a sampler but I use it as one.) If I need to do more I run that chop through Reason 3.0 (it has 2 different types of software samplers). I do it this way because my computer is strong and I can basically work with an entire song with out running out of memory or hardrive space. Thats 3 different manipulations on one sample. This gives me a mordern Hip Hop sound. If I want to get gutter, I then chop myself again and finish it of with 35 seconds of sample time on my Kurzweil 2500s.
If your money is tight go Software.
If you got cake, go both.
Hope this helps.
JGonz
Check out some of my work here:
http://www.myspace.com/jgonztheemperor